Power-assisted inflation assembly for sphygmomanometers

ABSTRACT

In a sphygmomanometer, the improvement which comprises a tube interconnecting the air line, leading to the inflatable cuff, and the air-introducing bulb by means of an interconnecting channel, with the channel having inner diameters at its ends at least equal to the inner diameters of its connecting elements and tapering centrally to define a constricted throat, and an airintake tube disposed at right angles to the throat axis and affording air intercommunication between the throat and the exterior of the tube. The air-intake tube is further provided with a sleeve valve to selectively close off communication of the throat with the exterior of the tube.

United States Patent Panzer 1 June 20, 1972 [72] Inventor: Norman Panzer, 71 Blanchard Road,

South Orange, NJ. 07079 [22] Filed: May 4, 1971 [21] App]. No.: 140,163

[521 U.S.Cl. ...l28/2.05G [51] Int. Cl. ..A6lb 5/02 [58] Field of Search ..128/2.05 G, 2.05 C, 2.05 M,

2,077,024 4/1937 Tanneretal ..417/15l 3,241,152 3/1966 Hay ..128/2.05 G 3,252,459 5/1966 Hay 3,563,674 2/1971 Moffat et a1.

Primary Examinerl(yle L. Howell Atlamey-Sydney B. Schlessel ABSTRACT In a sphygmomanometer, the improvement which comprises a tube interconnecting the air line, leading to the inflatable cufi, and the air-introducing bulb by means of an interconnecting channel, with the channel having inner diameters at its ends at least equal to the inner diameters of its connecting elements and tapering centrally to define a constricted throat, and an air-intake tube disposed at right angles to the throat axis and afi'ording air intercommunication between the throat and the exterior of the tube. The air-intake tube is further provided with a sleeve valve to selectively close off communication of the throat with the exterior of the tube.

8 Clains, 5 Drawing Figures POWER-ASSISTED INFLATION ASSEMBLY FOR SPHYGMOMANOMETERS BACKGROUND OF TI -IE INVENTION.

a. Field of the Invention This invention relates generally to to the field of medicine and more particularly to the use of a sphygmomanometer or blood-pressure device to measure the blood pressure of an individual. A standard sphygmomanometer comprises an inflatable cuff which is secured around a main artery of a patient, an air tube leading into the cuff from an air bulb or other air pumping means by which the cuff is inflated, and an air tube leading from the cuff interior to an air pressure gauge or manometer. for the the measurement of the pressure in the cuff. The customary procedure for the physician is to secure the cuff around the selected main artery, inflate the cuff by successive compressions of the air bulb until the flow of blood through the artery is completely stopped and the needle of the manometer registers a designated pressure, and then to slowly release or bleed the air from the cuff by means of an air leak or bleeder valve, meanwhile applying a stethoscope to the artery below the cuff, listening to the changing sounds as the blood again begins to flow through the artery and observing the changing air pressure by means of the manometer readings. In this manner the physician is able to determine the systolic and diastolic blood pressures of the patient. When the above procedures have been completed the air is then quickly released from the cufi through the bleeder valve and the cuff deflated and removed. It is the primary object of the present invention to provide for the inflation of the cufi more rapidly and with less effort on the part of the physician, and to control the bleeding or exhausting of air from the cuff more efiiciently for more exact observation of the effects of the changes in air pressure. This is accomplished by the introduction of a tube of specific structure between the air line, leading to the cuff, and the air bulb, whereby each volume of air pumped through the tube by compression of the air bulb causes the entraining of a substantially greater volume of air into the tube from the outer atmosphere, and thence through the air line to the cuff, thereby resulting in a more rapid inflation of the cuff with considerably less effort on the part of the physician.

b. Prior art In the present state of the art the proper inflation of the sphygmomanometer cufl requires, at the least, between 12 to 16 compressions of the air bulb on the part of the physician, depending on the individual patient, representing a substantial expenditure of time and effort. With many patients to be examined, or with repeated examinations of a patient, as during a surgical procedure, the physical efiorts on the part of the physician can become very tiring, and a substantial amount of time can be unnecessarily lost. Examination of the prior art fails to reveal any improvement or advance whereby air to inflate the cufl" is introduced other than that actually pumped from the air bulb or other form of air pump. The advantages of the present invention over the prior art, therefore, lie in the more rapid inflation of the sphygmomanometer cuff, reduced effort on the part of the physician or operator in the inflation of the cuff, and a more gradual release or air from the cuff for a more accurate determination of blood pressure.

BRIEF SUMMARY OF THE INVENTION My invention comprises the introduction, into the air line of the sphygmomanometer leading to the inflatable cuff, of a tube of the Venturi type provided with a interconnecting channel which, at its ends, is of inner diameters at least equal to the air line and air bulb inner diameters and which tapers centrally to define an intermediate constricted or reduced throat, with an air-intake tube extending at right angles to the axis of the channel and affording air intercommunication between the throat and the exterior of the tube, or outer atmosphere. The air-intake tube is further provided with valve means whereby it may be selectively closed off.

The principal object of my invention, therefore, lies in provision of a tube of the Venturi type disposed between the air line of a sphygmomanometer leading to its inflatable cuff and its air introducing bulb, whereby the volume of air passing through the tube with each compression of the bulb causes a substantially greater volume of air to be sucked into the tube from the atmosphere and to be similarly directed into the inflatable cuff.

A second important object of my invention lies in the provision of a tube as above described whereby the ratio of air volume introduced or entrained from the atmosphere to the volume of air introduced by compression of the bulb is determined by the relative inner diameters of the tube channel at its ends and at its throat.

A third important object of my invention lies in the provision of a tube of the type above described which is provided with means to selectively prevent introduction of air from the atmosphere into the tube.

Still another important object of my invention lies in the provision of a tube of the type described above which is inexpensive to manufacture and which can be utilized with existing types of sphygmomanometers.

These and other salient objects, advantages and functional features of my invention, together with the novel features of construction, composition and arrangement of parts will become more readily apparent from an examination of the following specification, taken with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS tube, partly in section;

FIG. 4 is an enlarged crosssectional view, taken on lines 4-4 of FIG. 2', and

FIG. 5 is a view similar to FIG. 4, but showing the sleeve valve in closed position on the air-intake tube.

Similar reference characters designate similar parts throughout the different views.

DETAILED DESCRIPTION OF THE INVENTION Illustrative of my invention, there is shown in FIG. I a sphygmomanometer 10 comprising an inflatable sleeve or cuff 12 secured around the ann 14 of the patient. The cuff 12 is connected interiorly to a flexible air line 16 leading to a suitable type of manometer l8, and by a flexible air line 20 to a combined air leak and and valve 22, also known as a bleeder valve, which is secured in and to an air bulb 24 having the customary valve 24A, as indicated. An available type of air leak and valve, such as shown here, in combination with an air bulb, is shown and described in US. Pat. No. 2,006,878, but other suitable types may be substituted if desired.

Disposed intermediate the air line 20 and the valve 22 there is provided a cylinder or tube 26 of the Venturi type, in airtight engagement at one end to the line 20 and at its other end to the valve 22, and affording direct flow of air from the bulb 24 to the cuff 12 by means of the channel 28 extending therethrough. The channel 28 is tapered centrally to define a constricted throat 30, and an extension of the tube 26, designated as an air intake, or air-entraining, tube 32 is disposed at right angles to the axis of the channel 28 and forms a direct communication between the throat 30 and the exterior ofthe tube 26.

The tube 32 is provided with a plurality of openings or bores 34 in its wall 36. As shown by FIGS. 2-5, a sleeve valve 38. provided with an enlarged head 40, is mounted around the tube 32 and is frictionally slidable thereon, so that pressure on the head 40 causes the valve 38 to enclose the tube 32 completely, as shown in FIG. 5, to close off entry of air into the tube 26 through the bores 34, while raising the valve 38 to clear the bores 34, as shown in FIG. 4, affords air communication between the throat 30 and the exterior of the tube 26.

The inner wall 44 of the tube 26 is provided at its end 46 with a peripheral recess 48 defining a terminal rim 50, for airtight engagement of the end 46 with the valve 22, and at the other end 52 of the tube 26 its outer wall 54 is provided with a peripheral recess 56 defining a terminal rim 58 for air-tight engagement of the end 52 with the air line 20.

lt is also to be noted, for reasons which will hereinafter be disclosed, that section 60 of the channel 28, leading from the air bulb 24, tapers at a greater angle towards the throat 30, while section 62 of channel 28, extending from the throat 30 to the air line 20 tapers at a smaller angle.

The tube 26, including the air intake tube 32, is preferably composed of a single unit of molded plastic material, with the sleeve valve 38 made in the same manner, but this is not essen tial to the operation of my invention, and variations may be made which will be equally effective. For example, the tube 26 may be made of plastic material and the air intake tube 32 of a metal, such as aluminum, and inserted therein, or the entire assembly of tube 26 and intake tube 32 may be composed of a suitable metal, such as aluminum or the like, with the sleeve valve 38 of either material. Similarly, the outer contour of the tube 26 is shown to be cylindrical, but such shape is not critical and may be varied to any other shape, or may even follow the contour of the channel 28.

As is well known in the art, in the flow of liquids and gases through a tube, where the velocity is greatest the pressure is the least. Thus, where a tube is not uniform in cross-section, that is, where a tube tapers to define a constricted area or throat, the velocity of the flow increases as the flow reaches the constricted throat, causing a corresponding decrease in pressure. and decreases after it passes the constricted throat, with a corresponding increase in pressure. The principle has been applied in Venturi meters for measuring the quantity of fluid flowing in a tube by measuring the difi'erence in pressure between two adjacent sections of different cross-sectional areas. Utilizing the underlying principle for the flow of air, where the constricted area is provided with an intake tube opening into the atmosphere, as the air directed through the main tube reaches the constricted area and its velocity increases its pressure decreases below atmospheric pressure, causing air to be entrained or sucked in from the atmosphere through the intake tube, thereby increasing the volume of air passing through the tube. in the application of this principel it has been found that where the diameter of the channel 28 at its ends 46 and 52 is three to four times the diameter at the throat 30, the volume of air sucked in from the atmosphere is approximately three times the volume of air passing directly through the tube 26 from the bulb 24. Thus, a single compression of the bulb 24 serves to direct four times the volume of air emanating from the bulb 24 into the cuff l2, and where, in the present types of sphygmomanometers 12 to 16 compressions of the bulb 24 are required to inflate the cuff 12 to the required pressure, no more than 3 or 4 compressions of the bulb 24 are required with my invention, to achieve the same result.

In the embodiment shown in the drawings, with the inner diameter of the air line 20 and valve 22 being 3 mms, I prefer a tube 26 having an inner diameter at its ends 46 and 52 of 3 mms, and an inner diameter at the throat of 1 mm, with the inner diameter of the air intake tube 32 being substantially the same as that of the throat 30. it is to be noted, further, that the angle of convergence of the channel 28 before the throat 30 is preferred to be approximately 25 to 30 from the horizontal, while the angle of divergance behind the throat 30 is more gradual, on the order of to 8. These angles of convergence and divergence are not critical for the operation of my invention, but serve to illustrate a favored arrangement, the contours having the effect of rapidly increasing the velocity of the air flow from the air bulb 24 as it nears the throat 30, and

more slowly decreasing the velocity as the combined original and entrained air leave the throat 30.

It is also further to be understood that the size of the tube 26 may be increased, with corresponding increase of the respective inner diameters in the same or a similar ratio.

OPERATION OF THE INVENTION In the operation of my invention for determining a patient's blood pressure, the cuff 12 is first secured around the arm 14 of the patient over a main artery, the air leak valve 22 closed and the sleeve valve 38 raised until the bores 34 are visible. With stethoscope applied to the artery below the cuff 12, the physician compresses the air bulb 24 to inflate the cuff 12 until the flow of blood through the artery is stopped and the required pressure noted on the manometer 18. As the air from the bulb 24 passes through the tube throat 30 its velocity increases and pressure decreases below atmospheric pressure, causing air to be sucked into the tube 26 through the intake tube 32, at the ratio of 3 volumes of atmospheric air to 1 volume of air passing from the bulb 24. Thus, 3 to 4 compressions of the air bulb 24 are sufficient to inflate the cuff 12 to required air pressure, instead of 12 to 16 compressions as formerly. The physician then rotates the screw of the air leak valve 22 to permit air to escape slowly from the cuff l2, meanwhile observing the manometer readings and listening to the sounds as the blood begins to flow through the artery, observing the pressure readings for the systolic and for the diastolic pressures. As the air passes from the cuff 12 through the throat 30 of the tube 26 its velocity again increases and pressure decreases, causing additional atmospheric air to be sucked into the tube 26 and thereby further slowing up the escape of air from the cuff l2 and enabling the physician to obtain more precise readings of blood pressure than is possible with the valve 22 alone.

After all blood pressure readings have been taken the air leak valve 22 is fully opened and the sleeve valve 38 depressed to close 0E the bores 34 in the intake tube 32, as shown in FIG. 5, so that its bottom edge 42 abuts the tube 26, whereupon the cuff l2 deflates more rapidly, since only air from the cuff 12 now passes through the tube 26 to the valve 22, and the cuff I2 is then removed from the patient.

From the foregoing it is obvious that the embodiment shown and described is by way of illustration and not of limitation, and that various changes may be made in the construction, composition and arrangement of parts without limitation upon or departure from the spirit and scope of the invention, or sacrificing any of the advantages thereof inherent therein, all of which are herein claimed.

Having described my invention, I claim:

1. In a sphygmomanometer of the type described, the combination of an inflatable cuff, an air line leading to the inflatable cuff, a pressure indicating means in communication with said inflatable cuff, an air introducing and exhausting means and a tube secured in air-tight engagement between said air line and said air introducing and exhusting means, and provided with a channel therethrough affording intercommunication between the air line and the air introducing and exhausting means, the channel tapering intermediately of its ends to define a constricted throat, and means to provide intercommunication between the throat and the exterior of the tube thereby to allow ambient air to be drawn into said channel to increase the volume of air introduced into said cuff.

2. The combination as described in claim 1, the means to provide intercommunication between the throat and the exterior of the tube comprising a secondary tube opening into the throat at one end thereof and extending out of the main tube.

3. The combination as described in claim 2, the secondary tube being disposed at right angles to the axis of the throat.

4. The combination as described in claim 3, the secondary tube extending beyond the surface of the main tube and provided with means to selectively close off intercommunication of air between the throat and the exterior of the main tube.

divergence of the tube channel leading away from the throat in the direction of the inflatable cufl.

7. The combination as described in claim 1, the inner diameters of the tube channel at the tube ends being at least equal to the inner diameter of the air line.

8. The combination as described in claim 7, the inner diameters of the tube channel at the tube ends being at least 3 times the inner diameter of the constricted throat. 

1. In a sphygmomanometer of the type described, the combination of an inflatable cuff, an air line leading to the inflatable cuff, a pressure indicating means in communication with said inflatable cuff, an air introducing and exhausting means and a tube secured in air-tight engagement between said air line and said air introducing and exhusting means, and provided with a channel therethrough affording intercommunication between the air line and the air introducing and exhausting means, the channel tapering intermediately of its ends to define a constricted throat, and means to provide intercommunication between the throat and the exterior of the tube thereby to allow ambient air to be drawn into said channel to increase the volume of air introduced into said cuff.
 2. The combination as described in claim 1, the means to provide intercommunication between the throat and the exterior of the tube comprising a secondary tube opening into the throat at one end thereof and extending out of the main tube.
 3. The combination as described in claim 2, the secondary tube being disposed at right angles to the axis of the throat.
 4. The combination as described in claim 3, the secondary tube extending beyond the surface of the main tube and provided with means to selectively close off intercommunication of air between the throat and the exterior of the main tube.
 5. The combination as described in claim 4, the means to selectively close off intercommunication comprising a plurality of bores in the wall of the secondary tube and a sleeve valve mounted on the secondary tube, the sleeve valve being frictionally slideable thereon between a position exposing the bores and a position enclosing the bores.
 6. The combination as described in claim 1, the angle of convergence of the tube channel leading to the throat in the direction of the inflatable cuff being greater than the angle of divergence of the tube channel leading away from the throat in the direction of the inflatable cuff.
 7. The combination as described in claim 1, the inner diameters of the tube channel at the tube ends being at least equal to the inner diameter of the air line.
 8. The combination as described in claim 7, the inner diameters of the tube channel at the tube ends being at least 3 times the inner diameter of the constricted throat. 